Chandra observations of the supermassive black hole in the nucleus of IC 1459 show a weak (Lx = 8 × 1040 ergs s -1, 0.3-8 keV), unabsorbed nuclear X-ray source, with a slope T = 1.88 ± 0.09, and no strong Fe K line at 6.4 keV (EW < 382 eV). This describes a normal active galactic nucleus (AGN) X-ray spectrum but lies at 3 × 10-7 below the Eddington limit. The spectral energy distribution of the IC 1459 nucleus is extremely radio-loud compared to normal radio-loud quasars. The nucleus is surrounded by a hot interstellar medium (kT ∼ 0.5-0.6 keV) with an average density of 0.3 cm-3, within the central ∼180 pc radius, which is comparable to the gravitational capture radius, rA ∼ 140 pc. We estimate that for a standard AGN efficiency of 10%, the Bondi accretion would correspond to a luminosity of ∼6 × 1044 ergs s-1, nearly 4 orders of magnitude higher than LX. ADAF solutions can explain the X-ray spectrum, but not the high radio/X-ray ratio. A jet model fits the radio-100 μm and X-ray spectra well. The total power in this jet is ∼10% of L Bondi, implying that accretion close to the Bondi rate is needed.
Fabbiano G., Elvis M., Markoff S., Siemiginowska A., Pellegrini S., Zezas A., et al. (2003). The X-ray-faint emission of the supermassive nuclear black hole of IC 1459. THE ASTROPHYSICAL JOURNAL, 588(1 I), 175-185 [10.1086/374040].
The X-ray-faint emission of the supermassive nuclear black hole of IC 1459
Pellegrini S.;
2003
Abstract
Chandra observations of the supermassive black hole in the nucleus of IC 1459 show a weak (Lx = 8 × 1040 ergs s -1, 0.3-8 keV), unabsorbed nuclear X-ray source, with a slope T = 1.88 ± 0.09, and no strong Fe K line at 6.4 keV (EW < 382 eV). This describes a normal active galactic nucleus (AGN) X-ray spectrum but lies at 3 × 10-7 below the Eddington limit. The spectral energy distribution of the IC 1459 nucleus is extremely radio-loud compared to normal radio-loud quasars. The nucleus is surrounded by a hot interstellar medium (kT ∼ 0.5-0.6 keV) with an average density of 0.3 cm-3, within the central ∼180 pc radius, which is comparable to the gravitational capture radius, rA ∼ 140 pc. We estimate that for a standard AGN efficiency of 10%, the Bondi accretion would correspond to a luminosity of ∼6 × 1044 ergs s-1, nearly 4 orders of magnitude higher than LX. ADAF solutions can explain the X-ray spectrum, but not the high radio/X-ray ratio. A jet model fits the radio-100 μm and X-ray spectra well. The total power in this jet is ∼10% of L Bondi, implying that accretion close to the Bondi rate is needed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
